268 research outputs found

    Amelioration of experimental allergic encephalomyelitis (eae) by phase 2 enzyme inducer

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    The pathology of multiple sclerosis (MS) is characterized by an inflammatory mononuclear infiltration in the white matter. There has been converging evidence of the oxidative stress playing a role in the onset and progression of MS. We postulated that the decreasing oxidative stress might help in the management of MS. We know that the induction of phase 2 enzymes decreases the oxidative stress. The experimental allergic encephalomyelitis (EAE) induced in the Lewis rats were used to test this hypothesis. The 24 animals were placed into two groups: 1) those on normal rat chow, 2) those on rat chow containing 7.5 g/kg of tetra-butylhydroxyanisole (BHA), a food preservative. All the animals were administered 100 µg of guinea pig myelin basic protein in their tails to induce EAE and examined daily in a double blinded fashion. On 29th day of the induction, the animals were sacrificed, blood collected for glutathione (GSH) measurements and tissues collected for histology. All the animals, regardless of their diet status, developed symptoms of EAE on different days ranging from tail weakness to hind limb paralysis and all of them reached remission of acute EAE before the 28th day of induction. The non-BHA fed animals developed hind limb weakness in 8 animals and hind limb paralysis in 4 cases, while that of BHA fed group developed tail paralysis in 2, hind limb weakness in 2 and hind limb paralysis in 8 cases. The histology of the non-BHA group correlated well with the clinical symptoms of perivascular mononuclear infiltration. However, the BHA group revealed complete pathological recovery. Animals with BHA in the diet had significantly raised GSH, indicating the induction of phase 2 enzymes. We conclude that dietary phase 2 enzyme inducers show potential therapeutic benefits in EAE and should be examined for this role in MS

    Ground-based ISAR imaging of cooperative and non-cooperative sea vessels with 3-D rotational motion

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    Includes bibliographical references (leaves 175-188).Inverse Synthetic Aperture Radar (ISAR) images of sea vessels are a rich source of information for radar cross section (RCS) measurement and ship classification. However, ISAR imaging of sea vessels is a challenging task because the 3-D rotational motion of such vessels often gives rise to blurring. Blurry ISAR images are not desirable because they lead to inaccurate parameter estimation, which reduces the probability of correct classification. The objective of this thesis is to explain how 3-D rotational motion causes blurring in ISAR imagery and to develop effective techniques for imaging cooperative and non-cooperative sea vessels for RCS measurement and ship-classification purposes respectively. Much research has been done to investigate the effect of 3-D rotational motion on an ISAR image under the assumption that an object's axis of rotation is constant over the coherent processing interval (CPI). In this thesis, a new quaternion-based system model is proposed to characterise the amount of blurring in an ISAR image when a sea vessel possesses 3-D rotational motion over a CPI. Simulations were done to characterise the migration of a scatterer through Doppler cells due to the time-varying nature of the Doppler generating axis of rotation. Simulation results with realistic 3-D rotational motion show substantial blurring in the cross-range dimension of the resulting ISAR image, and this blurring is attributed to the time-varying nature of the angle of the Doppler generating axis of rotation and the object's rotation rate over the CPI

    Genetic Based Experimental Investigation on Finishing Characteristics of AlSiCp-MMC by Abrasive Flow Machining

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    Implementing non-conventional finishing methods in the aircraft industry by the abrasive flow machining (AFM) process depends on the production quality at optimal conditions. The optimal set of the process variables in  metal-matrix-composite (MMC) for a varying reinforcement percentage removes the obstructions and errors in the AFM process. In order to achieve this objective, the resultant output functions of the overall process using every clustering level of variables in a model are configured by using genetic programming (GP). These functions forecast the data to vary the percent of silicon carbide particles (particles without experimentation obtaining the output functions for material removing rates and surface roughness changes of Al-MMCs machined with the AFM process by using GP. The obtained genetic optimal global models are simulated and, the results show a higher degree of accuracy up to 99.97% as compared to the other modeling techniques.   &nbsp

    Modern applications of profit-sale (Bayʿ murābaḥah) from a Maqāsid Sharīʿah perspective

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    This paper looks into profit-sale (murābaḥah), a nominal sale contract in Islam, in search for Shari'ah objectives embedded in the corpus and in the terms and conditions of the contract. In light of these objectives, applications of the profit-sale contract as a financing tool by the Islamic Finance Institutions (IFIs) are examined. The study discovers that some modern applications bypass the primary Shari'ah objectives of a sale contract, such as the seller taking liability of possible risks and having real possession of the items on sale. Contrary to this, the seller transfers his liability to the customer, and takes possession (qabḍ) of the goods on paper only, instead of possession in the real sense. Such applications distort the mode of trading real goods into a mere disguise for an increase on credit or riba

    Study the effect of volume fraction concentration and particles materials on thermal conductivity and thermal diffusivity of nanofluids.

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    Nanofluids, a mixture of nanoparticles and fluids, have exceptional potential to improve their effective thermal conductivity and thermal diffusivity, aluminum and aluminum oxide nanofluids with five different volume fractions of nanoparticle suspensions in different base fluids, i.e., distilled water, ethylene glycol (EG), and ethanol were prepared by mixing nanopowder and base fluids. Sonication with high-powered pulses was used to ensure the dispersion of nanoparticles in good uniformity in the base fluids. The hot wire-laser beam displacement technique was used to measure thermal conductivity and thermal diffusivity of the prepared nanofluids. The effects of the volume fraction concentration and particle materials on the thermal conductivity and thermal diffusivity of nanofluids were determined. The results showed that the thermal conductivity and thermal diffusivity increased linearly with increasing volume fraction concentration of nanoparticles in the respective base fluids. In addition, the thermal conductivity and thermal diffusivity increased faster in the Al2O3 nanofluids than in all the three base fluids

    Modeling the factors affecting cereal crop yields in the Amhara National Regional State of Ethiopia.

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    Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.The agriculture sector in Amhara National Regional State is characterised by producing cereal crops which occupy the largest percentage (84.3%) of the total crop area cultivated in the region. As a result, it is imperative to investigate which factors influence the yields of cereal crops particularly in relation to the five major types of cereals in the study region namely barley, maize, sorghum, teff and wheat. Therefore, in this thesis, using data collected by the Central Statistical Agency of Ethiopia, various statistical methods such as multiple regression analysis were applied to investigate the factors which influence the mean yields of the major cereal crops. Moreover, a mixed model analysis was implemented to assess the effects associated with the sampling units (enumeration areas), and a cluster analysis to classify the region into similar groups of zones. The multiple regression results indicate that all the studied cereals mean yields are affected by zone, fertilizer type and crop damage effects. In addition to this, barley is affected by extension programme; maize crop by seed type, irrigation, and protection of soil erosion; sorghum and teff crops are additionally affected by crop prevention method, extension programme, protection of soil erosion, and gender of the household head; and wheat crop by crop prevention methods, extension programme and gender of the household head. The results from the mixed model analysis were entirely different from the regression results due to the observed dependencies of the cereals mean yields on the sampling unit. Based on the hierarchical cluster analysis, five groups of classes (clusters) were identified which seem to be in agreement with the geographical neighbouring positions of the locations and the similarity of the type of crops produced

    Modern applications of profit-sale (bay murabahah) from a maqasid Shari' ah perspective

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    This paper looks into profit-sale (murābaḥah), a nominal sale contract in Islam, in search for Sharīʿah objectives embedded in the corpus according to the terms and conditions of the contract. In light of these objectives, applications of the profit-sale contract as a financing tool by Islamic Finance Institutions (IFIs) are examined. The study discovers that some modern applications bypass the primary Sharīʿah objectives of a sale contract, such as the seller taking liability for possible risks and having real possession of the items on sale. Contrary to this, the seller transfers his liability to the customer and takes possession (qabḍ) of the goods on paper only instead of possession in the real sense. Such applications distort the mode of trading real goods into a mere disguise for an increase in credit or riba

    Evaluation of Tribological aspects of Al-Si 12 alloy and their Metal Matrix hybrid Composites produced by Liquid-metal Forging Method

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    Particulate Aluminium Metal Matrix Composites (Al-MMC) have emerged as advanced engineering materials in view of their improved properties. Ceramic reinforced Al-MMC were more suitable because of being economical and exhibiting isotropic properties. Al-MMCs manufacturing methods are expensive, demand skilled and complex operations and vortex liquid metallurgy results into higher porosity. The liquid-metal forging/squeezed casting of stirred molten slurry can eliminate porosity as molten metal is pressurized during solidification forming near net shapes. During many instances, influence of process parameter (PP)s on mechanical part properties is being studied. In the present study, composites were produced using Al-Si12 alloy as base material, aluminium oxide and silicon carbide particles as reinforcements by varying the PPs. Tribological tests were conducted under dry sliding condition at room temperature showed hard reinforcements in Al alloy reduced the wear rate (WR) and increased the coefficient of friction (f) for all PPs. For PPs, increasing the squeeze pressure and decreasing the pouring and die preheating temperature resulted in a reduction of WR and f with an increase in normal load and sliding velocity. Initially f falls and then raised with an increase in normal load, but only raised with growing sliding velocity compared to Aluminium base material.

    Application of UPFC to Improve the LVRT Capability of Wind Turbine Generator

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    Variable speed wind turbine generators installation has been significantly increased worldwide in the last few years. Voltage sag at the grid side may call for the disconnection of the wind turbine from the grid as under such faults it may not comply with the recent developed grid codes for wind energy conversion systems (WECS). In this paper, a Unified Power Flow Controller (UPFC) is applied to improve the low voltage ride through (LVRT) capability of doubly fed induction generator (DFIG)-based WECS during voltage sag at the grid side. Simulation is carried out using MATLAB/Simulink software. Results show that UPFC can significantly improve the LVRT capability of DFIG-based WECS and hence maintaining wind turbine connection to the grid during certain levels of voltage sag at the grid side
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